The present invention relates to a dual-stage actuation system for a disc drive, and more particularly to a microactuator for effecting fine positioning of an entire E-block.
Radial track density in disc drives continues to increase, resulting in an increased need for extremely precise head positioning systems. Voice coil motor (VCM) actuators are well-suited to effect coarse positioning, but lack the resolution to finely position and center a transducing head over a selected track. This inadequacy has led to a variety of proposals for a second stage microactuator to effect fine positioning in high track density disc drives.
The microactuator proposals have taken several forms, from an electrostatic microactuator attached to the slider carrying the transducing head, to a piezoelectric microactuator installed at the head suspension mounting block at a distal end of the actuator arm. These proposals all associate the microactuator with components of each individual actuator arm, which imposes an artificial minimum thickness constraint on the actuator arms. In other words, the actuator arms must be thick enough to accommodate the microactuator. This constraint contradicts the general design objective of minimizing the mass of the actuator arms in the disc drive system. In addition, the proposed designs locate the microactuator a substantial distance from the E-block pivot, introducing head skew and failing to maximize the displacement of the head for a corresponding movement of the microactuator.
Therefore, there is a need in the art for a dual-stage actuation system including a microactuator that does not limit the minimum thickness of the actuator arms, minimizes head skew in fine positioning operations, and maximizes head displacement for a corresponding microactuator movement.